[GitHub] [pulsar] michaeljmarshall commented on a diff in pull request #20903: [pip][design] PIP 289: Secure Pulsar Connector Configuration

["michaeljmarshall (via GitHub)" <gi...@apache.org>]

michaeljmarshall commented on code in PR #20903:
URL: https://github.com/apache/pulsar/pull/20903#discussion_r1287631218


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+# PIP 289: Secure Pulsar Connector Configuration
+# Background knowledge
+
+Pulsar Sinks and Sources (a.k.a. Connectors) allow you to move data from a remote system into and out of a Pulsar cluster. These remote systems often require authentication, which requires secret management. 
+
+The current state of Pulsar Connector secret management is fragmented, is not documented in the "Pulsar IO" docs, and is not possible in certain cases. This PIP aims to address these issues through several changes.
+
+The easiest way to show the current short comings is by way of example.
+
+## Elasticsearch Example
+Here is the current way to deploy an Elasticsearch Sink without the use of plaintext secrets:
+
+```shell
+$ bin/pulsar-admin sinks create \
+    --tenant public \
+    --namespace default \
+    --sink-type elastic_search \
+    --name elasticsearch-test-sink \
+    --sink-config '{"elasticSearchUrl":"http://localhost:9200","indexName": "my_index"}' \
+    --secrets '{"username": {"MY-K8S-SECRET-USERNAME": "secret-name"},"password": {"MY-K8S-SECRET-PASSWORD": "password123"}}'
+    --inputs elasticsearch_test
+```
+
+When run targetting Kubernetes, the above works by mounting secrets `MY-K8S-SECRET-USERNAME` and `MY-K8S-SECRET-PASSWORD` into the sink pod container as [environment variables](https://github.com/apache/pulsar/blob/82237d3684fe506bcb6426b3b23f413422e6e4fb/pulsar-functions/secrets/src/main/java/org/apache/pulsar/functions/secretsproviderconfigurator/KubernetesSecretsProviderConfigurator.java#L85-L99):
+
+```shell
+username=secret-name
+password=password123
+```
+
+Those environment variables are then [injected](https://github.com/apache/pulsar/blob/674655347da95305cf671f0696f113dcca88b44d/pulsar-io/common/src/main/java/org/apache/pulsar/io/common/IOConfigUtils.java#L67-L78) into the config when it is loaded at runtime based on [annotations](https://github.com/apache/pulsar/blob/b7eab9469177eda2c56e36bb9871aab48a17d4ec/pulsar-io/elastic-search/src/main/java/org/apache/pulsar/io/elasticsearch/ElasticSearchConfig.java#L99-L113) on the `ElasticSearchConfig`.
+
+### Problem
+
+The annotation approach, which is the only way to inject secrets into connectors, requires that all secret fields are annotated with `sensitive = true` and that all secret fields are at the top level of their configuration class. However, the Elasticsearch config contains an `ssl` field that has nested secrets. See:
+
+```json
+{
+      "elasticSearchUrl": "http://localhost:9200",
+      "indexName": "my_index",
+      "username": "username",
+      "password": "password",
+      "ssl": {
+        "enabled": true,
+        "truststorePath": "/pulsar/security/truststore.jks",
+        "truststorePassword": "truststorepass",
+        "keystorePath": "/pulsar/security/keystore.jks",
+        "keystorePassword": "keystorepass"
+      }
+}
+```
+
+Because `truststorePassword` and `keystorePassword` are not at the top level, we do not currently have a secure way (i.e. non-plaintext) to configure those settings.
+
+## RabbitMQ Example
+
+Another relevant example shows how the Pulsar code base has not consistently implemented secret management for connectors. For the RabbitMQ Sink, the sensitive fields are [annotated correctly](https://github.com/apache/pulsar/blob/82237d3684fe506bcb6426b3b23f413422e6e4fb/pulsar-io/rabbitmq/src/main/java/org/apache/pulsar/io/rabbitmq/RabbitMQAbstractConfig.java#L61-L73), but the configuration is not loaded via the `IOConfigUtils#loadWithSecrets` method, which means the only way to load rabbit secrets is as plaintext values in the config.
+
+## Kafka Connect Adapter Example
+
+The final relevant example is the Kafka Connect Adapter. This adapter allows you to run Kafka Connectors in Pulsar Connectors. Because of the recursive nature of these connectors, the configuration for the wrapped connector is stored in a map named [kafkaConnectorConfigProperties](https://github.com/apache/pulsar/blob/55523ac8f31fd6d54aacba326edef1f53028877e/pulsar-io/kafka-connect-adaptor/src/main/java/org/apache/pulsar/io/kafka/connect/PulsarKafkaConnectSinkConfig.java#L59-L62). Because this field is an arbitrary map, we cannot rely on the Pulsar `sensitive` annotation flag to determine whether to load the secret when building the config class.
+
+# Motivation
+
+Increase Pulsar Function security by giving users a way to configure Pulsar Connectors with non-plaintext secrets.
+
+The recent [CVE-2023-37579](https://github.com/apache/pulsar/wiki/CVE%E2%80%902023%E2%80%9037579) resulted in the potential to leak connector configurations. Because we do not always provide a way to configure connector configuration in the connector's secrets map, leaking the configuration meant leaking secrets.
+
+# Goals
+
+## In Scope
+
+* Provide users with a secure way to configure official Pulsar Connectors as well as third party connectors.
+* Improve documentation to reflect the current state of secrets management in Pulsar Connectors.
+* Only sinks and sources will benefit from this change.
+* Only the `JavaInstanceRunnable` class will benefit from this change.
+
+## Out of Scope
+
+* This PIP will not prevent users from configuring secrets via insecure methods, such as plaintext configuration.
+* Functions are out of scope because they do not need arbitrary secret injection. Functions can already access secrets through the `Context#getSecret` method.
+* Python and Go Function Runtimes--sinks and sources are not typically written in these languages.
+
+# High Level Design
+
+* Add a new secrets injection mechanism which allows for arbitrary secret injection into the connector configuration at runtime.
+* Update existing, official connectors to properly use the already available secret injection mechanism.
+* Fix the documentation for the existing secrets management methods.
+
+# Detailed Design
+
+## Design & Implementation Details
+
+In order to add a new way to inject, or interpolate, secrets, we need to add a new method to the `SecretsProvider` interface, which can be implemented by users, but is not exposed to functions/connectors. This new method will be used to first determine if a secret should be interpolated for a given value, and if so, return the interpolated value. If the value is not a secret, or the secret does not exist, the method will return null. The notable difference for this method is that it does not have a "path" to the secret. Therefore, the existing `secrets` map might not apply for certain use cases. In the environment variable scenario, this is a natural fit because the `value` can be interpreted as the name of the environment variable. For usage of the new configuration mechanism, see the [cli](#cli) section.
+
+In order to add support for the existing `sensitive` annotation, I propose fixing all the connectors that have explicit secrets in their configurations.
+
+Fixing the documentation will be a matter of updating the existing documentation to reflect the current state of the code.
+
+## Public-facing Changes
+
+### Public API
+
+#### Add new method to SecretsProvider Interface
+
+Add the following method to the `SecretsProvider` interface:
+
+```java
+interface SecretsProvider {
+    /**
+     * If the passed value is formatted as a reference to a secret, as defined by the implementation, return the
+     * referenced secret. If the value is not formatted as a secret reference or the referenced secret does not exist,
+     * return null.
+     *
+     * @param value a config value that may be formatted as a reference to a secret
+     * @return the materialized secret. Otherwise, null.
+     */
+    default String interpolateSecretForValue(String value) {

Review Comment:
   I provided an implementation here: https://github.com/apache/pulsar/pull/20901. This method will be called by Pulsar.



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